This invention relates to decontamination and sterilization devices and, more particularly, to a method and apparatus for sterilizing articles of mail that may be tainted with anthrax or other pathogens.
A single letter contaminated with anthrax or similar pathogens can cause serious health issues or even death to humans. In fact, a single letter may include thousands of times more than the lethal dose of anthrax. The threat of safety relative to the delivery of mail was accented by the anthrax infections following the historic terrorist attacks against the United States on Sep. 11, 2001. Several people were infected with anthrax as a result of letters containing the deadly pathogens. Postal offices and other businesses had to be shut down and fully sterilized. Anthrax in a single letter can cross-contaminate other articles of mail, postal sorting equipment, and the like. This is a significant problem in view of the 680 million pieces of mail handled by the U.S. Postal Service every day.
Various devices have been proposed for sterilizing medical equipment and other articles. Although assumably effective for their intended purposes, the existing devices are not suitable for sterilizing mail at the initial point of mail deposit or without damaging the mail. More particularly, the use of steam heat or intense dry heat would irreversibly damage mail. Further, chemical sterilization with ethylene oxide gas avoids the damages associated with heat sterilization but requires long cycle times and the handling of harsh chemicals. These disadvantages would be unacceptable for use in mass mail processing. Sterilization with gamma radiation, while effective, would be prohibitively expensive for use in the decentralized mail processing and delivery industry.
Therefore, it is desirable to have a method and apparatus for sterilizing mail quickly and without damaging the mail. Further, it is desirable to have a method and apparatus for sterilizing mail without generating excessive heat or pollution. In addition, it is desirable to have a method and apparatus for sterilizing mail that may be used in the mail sorting process.
A method and apparatus for sterilizing mail according to the present invention includes a chamber defining an airtight enclosed space and having an entrance and exit through which mail may be conveyed. A vacuum pump is coupled to the chamber for withdrawing air from the chamber and an article of mail therein. This withdrawal of air reduces the air pressure in the chamber. An ozone gas generator is also coupled to the chamber and is capable of introducing ozone therein after all gases have been removed by the vacuum pump. Introducing ozone into the low pressure environment causes the ozone to permeate the article of mail very quickly as the ozone seeks to diffuse in even concentration throughout the chamber. Ozone is an unstable molecule that reacts with organic matter such as bacteria and viruses. This reaction destroys critical components of organisms, thereby being an effective sterilizing agent against anthrax within an article of mail. The highly reactive property of ozone makes sterilization very quick compared to other disinfectant methodologies. Following sterilization, the ozone is withdrawn from the chamber by another operation of the vacuum pump or with another fan such that the ozone is collected in an ozone filter. The filter includes a non-consumable catalyst such as manganese dioxide which converts the ozone into oxygen. The apparatus may be implemented using a single chamber or using multiple chambers connected by airlocks (multi-stage implementation).
Therefore, a general object of this invention is to provide a method and apparatus for sterilizing mail from anthrax or other pathogenic poisoning.
Another object of this invention is to provide a method and apparatus, as aforesaid, which sterilizes articles of mail quickly and without exposure of persons to harsh or harmful chemicals.
Still another object of this invention is to provide a method and apparatus, as aforesaid, which sterilizes articles of mail without damaging the articles of mail.
Yet another object of this invention is to provide a method and apparatus, as aforesaid, which sterilizes mail without generating excessive heat or pollution.
A further object of this invention is to provide a method and apparatus, as aforesaid, which may be integrated into a conventional mail sorting process.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, embodiments of this invention.